In the manufacture of glass envelopes for cathode ray tubes such as those utilized in television viewing sets, the glass envelope or bulb is manufactured in separate parts which are then united together by various processes. The viewing area or faceplate is manufactured in a press and contains a flanged edge that facilitates its attachment to the large end central portion of the bulb which is known as the funnel. The smaller end of the funnel is attached to a cylindrical glass tube known as the neck.
The glass neck tube is attached to the small end of the glass funnel by actually melting the respective ends of the glass as the parts are held in close proximity to one another. During the fusion process, the glass funnel and neck tube must be held in precise axial alignment consequently various holding devices or lathes are employed to provide the necessary alignment. In addition to providing the axial alignment, the lathe arrangement permits the glass parts to be rotated simultaneously so that a heat source can be evenly applied to the joint to be welded or fused together.
As the welding process commences, it is important that the end of the glass neck tube be in contact with the mating edge of the glass funnel because a small space or gap can cause a defective weld. A common defect is a small hole in the weld area which of course cannot be tolerated since the cathode ray tube depends upon an internal vacuum for successful operation.
The present invention minimizes the task of achieving proper alignment of the glass parts prior to and during the joining together or welding process. Thus rapid assembly techniques can be employed on a production line basis to produce vacuum tight welds.